The two major objectives of this proposal are to elucidate the structure of cell membranes and to study the mechanism of hormone action at the membrane level. It is proposed to examine the arrangement of the amino-phospholipids and proteins in various membranes by use of penetrating and non-penetrating chemical probes and cross-linking probes which react with amino groups. This study is aimed to determine how many of the amino-phospholipids are oriented on the inner and outer surface of the membrane, the neighbor frequency of these phospholipids, how many amino-phospholipids are closely associated with proteins and which specific proteins bind these polar lipids. Perturbation of the membrane will be followed by use of these chemical probes. The mechanism of hormone action on cell membranes will be carried out by a study of hormone binding to isolated erythrocytes, liver plasma membranes and isolated fat cells from rats and humans. The binding of catecholamines will be correlated with adenylate cyclase activity, lipolysis, and cation transport. Insulin and catecholamine binding will be studied in fat cells from obese and diabetic humans and compared to normals to see if hormone binding is altered. The influence of thyroxine on catecholamine binding and hormone response in isolated fat cells will be studied in order to elucidate the "permissive action" of thyroxine on the catecholamine response in adipose tissue. Structure-function relationships with catecholamines will be studied by comparing the binding of various catecholamine analogs and their ability to alter the hormone response. Alpha and beta adrenergic blockers will be studied to see which ones influence catecholamine binding and which ones influence catecholamine coupling to adenylate cyclase. Attempts will be made to isolate and purify the catecholamine receptor protein from liver and the erythrocyte plasma membrane.